Missing Edit options on recipes

In the "More" menu, find "Recipes, Meals, & Foods" and click it. In the Recipes tab of the page that results, find the recipe you want to edit, and click on it. In the upper right corner, find the 3 dots, and click on that. You should get something like this, where there is an "Edit" option:

If you notice, there's a button at the bottom of that recipe page, too, so you can log the recipe from there if you wish, rather than just by using "Add Food" in your diary.

Once someone - another MRP user - has scanned something, found that the food wasn't in the database, and has input that food associated with the bar code, I believe there is no way for you to edit the food and link it to the same bar code. If what they entered is incorrect, or outdated, or otherwise just wrong, you may be able to report it to MFP (and maybe they'll fix it eventually, but don't hold your breath), but I believe you can't fix the bar code. You can still input the food, have it in "My Foods" correctly, but you won't be able to access it via the scanner.

Not sure about this next, but I think in some cases the manufacturer will have the same named product with the same bar code in different countries, but a different product formulation in each of the countries, or different nutrition labels, because of how food formulation or labeling regulations differ between the countries. If that's so, there's no way to make the bar code scan be correct for everyone everywhere.

I literally never use the scanner. This is just one of the reasons. However, I know that many people find it very useful, with only minor impact from issues like this as long as they keep an eye on scan results.